Selective solid and impurity removal pretreatment method and system for oil slurry

Abstract

The invention provides a pretreatment method and system for selective solid and impurity removal of oil slurry. The pretreatment method comprises the following steps: dividing the oil slurry into a light component and a heavy component according to temperature; selectively hydrotreating the light components according to the sulfur content of the light components; mixing the heavy component with an organic polar solvent to form a mixed heavy component; filtering and settling the mixed heavy component for solid removal to obtain a permeation side component and a concentration side component, and mixing the concentration side component with the heavy component and an organic polar solvent; carrying out solvent removal on the permeation side component to obtain a filtered oil slurry heavy component; hydrotreating the filtered oil slurry heavy component to obtain a hydrogenated oil slurry heavy component; the selective solid and impurity removal pretreatment of the oil slurry is completed. According to the method, different types of oil slurry can be subjected to targeted deep solid removal and deep impurity removal, and the high-quality aromatic-rich component with relatively concentrated molecular weight distribution is obtained and is used as a preparation raw material of high-quality mesophase pitch and / or needle coke.

Description

Technical Field

[0001] This invention relates to the field of oil slurry pretreatment technology, and in particular to a method and system for selective deconsolidation and impurity removal pretreatment of oil slurry. Background Technology

[0002] Tricyclic and tetracyclic aromatic hydrocarbons with short side chains are ideal components for preparing precursors of carbon materials such as mesophase pitch and needle coke. They are widely available and can be enriched from various secondary petroleum products, including slurry oil, ethylene tar, coking wax oil, and furfural extract. However, these heavy oil resources have a complex composition, containing not only ideal components but also catalyst dust, olefins, saturated hydrocarbons, gums, asphaltenes, 1-2 ring light aromatic hydrocarbons, polycyclic aromatic hydrocarbons with 4 or more rings, long-chain tricyclic and tetracyclic aromatic hydrocarbons, and heteroatom compounds containing sulfur, nitrogen, oxygen, and metals. Therefore, the raw materials for heavy oil-based carbon material precursors are generally not directly obtainable and require separation and purification from heavy oil. The preparation of carbon material precursor raw materials, i.e., the refining of aromatic-rich raw materials through pretreatment technology, must overcome three key technologies: 1. Efficient separation of solid particles such as catalyst powder from heavy oil; 2. For raw materials with high content of non-ideal components, customized removal or conversion of all or part of non-ideal components such as gums, asphaltenes, olefins, polycyclic aromatic hydrocarbons (PAHs), and long-chain aromatic hydrocarbons, based on the target product; 3. For raw materials with low content of 3- to 4-cyclic PAHs, targeted enrichment of 3- to 4-cyclic PAHs can be carried out based on the fulfillment of the first and second key technologies. For non-ideal components in slurry oil, generally, depending on the specific properties and composition characteristics of the slurry oil, a combination of 2-3 processing units from desoldering, deasphalting, solvent extraction, distillation, and hydrorefining is adopted to obtain the ideal components. In some cases, to obtain even purer aromatic-rich components, a process flow combining 4-5 processing units is also used.

[0003] CN201310353779.0 employs a combined technology of solvent extraction, raffinate solvent recovery and treatment, and extractant solvent recovery combined with target product distillation to achieve solidification and aromatic enrichment; CN201510144811.3 employs a combined technology of subcritical or supercritical extraction, hydrodesulfurization, and delayed coking to achieve solidification and impurity removal; CN201210427726.4 employs filtration, hydrotreatment, and vacuum distillation for solidification and impurity removal. None of these combined processes achieve a comprehensive pretreatment technology for solidification, impurity removal, and aromatic enrichment of oil slurry.

[0004] CN202111162088.3 employs a combined technology of cross-flow filter with ceramic or metal membrane elements, vacuum distillation, and hydrotreating; CN201610970275.7 employs a combination of cracking reaction, fractionation, hydrodesulfurization, separation, and condensation reaction; CN201910896551.3 employs a combined process of deasphalting, solvent extraction, solidification treatment, fraction cutting, and hydrodesulfurization and nitrogen removal; EP20200154420 and US202016777031 employ a combined process of separation tower, hydrotreating, and aromatic extraction. The above technical solutions achieve the comprehensive goals of solidification, impurity removal, and aromatic enrichment through integrated pretreatment technology for oil slurry.

[0005] Oil slurry desolidification technologies mainly include filtration, sedimentation, and electrostatic separation. Filtration and sedimentation are generally effective for separating solid particles larger than 20 μm, while electrostatic separation is more suitable for separating ultrafine particles smaller than 10 μm. Because the catalyst particles in oil slurry have a wide particle size distribution, ranging from 0.1 to 100 μm with an average particle size of 20 μm, and the density of fine particles is comparable to that of the oil slurry, they are highly dispersed in the slurry. The presence of colloids, asphaltenes, and some polar compounds containing sulfur and nitrogen in the oil slurry, coupled with strong intermolecular hydrogen bonds and π-π conjugation forces, easily leads to the formation of aggregates that encapsulate the adsorbed solid particles, further enhancing the stability of the suspended particles. This makes efficient, rapid, and deep liquid-solid separation extremely difficult.

[0006] In current combined oil slurry pretreatment processes, regardless of whether physical interception, distillation, solvent precipitation, or electrostatic methods are used, deconsolidation is usually the first step in the pretreatment. This is due to two main factors: firstly, the presence of polar substances such as heteroatoms, colloids, and asphaltenes in the oil slurry raw material; and secondly, the limitations imposed by different deconsolidation methods. A single deconsolidation method cannot simultaneously remove particles from a wide range of particle sizes, thus hindering the achievement of deep deconsolidation.

[0007] Oil slurry impurity removal generally includes asphaltene removal, desulfurization, and nitrogen removal. Due to the high-temperature cracking process of catalytic cracking, the sulfur and nitrogen atoms in the residual sulfur and nitrogen compounds in the oil slurry are usually located in five- or six-membered aromatic rings, which are very similar in physical and chemical properties to aromatic hydrocarbons with the same number of rings. When the desulfurization reaction conditions are met, aromatic hydrocarbons will undergo saturation and ring-opening reactions. However, cyclic nitrogen-containing compounds are more chemically stable and more difficult to remove.

[0008] To achieve high desulfurization and denitrification rates, a loss of total aromatics, especially polycyclic aromatic hydrocarbons (PAHs), is often incurred. To avoid this loss, the depth of hydrogenation is typically controlled, making deep deimpurification impossible. Therefore, the challenge in deimpurification of catalytic cracking slurry oil lies in minimizing the loss of aromatics, particularly 3-4 ring effective aromatics, while simultaneously achieving deep desulfurization and denitrification. Currently, the common practice is to use the entire slurry fraction or a distillation process to "cut off the head and tail," followed by middle fraction hydrogenation for impurity removal. When using the entire fraction for hydrogenation, the desulfurization rate is generally controlled at around 60% without loss of aromatics, while the denitrification rate is only around 20%. However, when using the middle fraction for hydrogenation, in addition to resulting in low overall slurry oil utilization, the aromatics become lighter after hydrogenation, affecting the quality of subsequent carbonization products.

[0009] The longer the process, the higher the energy consumption, resulting in greater oil slurry loss and lower utilization. Existing oil slurry deconsolidation and impurity removal technologies have several problems and drawbacks. First, these methods often require high energy consumption and cost, and their processing efficiency is not high. Second, these methods may generate a large number of byproducts, for which there are no good utilization methods, resulting in low oil slurry utilization. In addition, for heavy oil slurries with high sulfur and nitrogen content, existing deconsolidation technologies often cannot deeply reduce their sulfur and nitrogen content, affecting the further utilization of the oil slurry. Therefore, the core competitiveness of current oil slurry pretreatment lies in how to obtain high-quality aromatic-rich components with deep consolidation and impurity removal in a more economical form, under the premise of shorter process or lower energy consumption, for the preparation of mesophase pitch or high-quality needle coke, for the same oil slurry raw material.

[0010] In summary, oil slurry currently has a wide range of sources and diverse properties. Existing oil slurry pretreatment methods either have long processes resulting in low utilization rates or short processes that are only suitable for specific raw materials. There is currently no pretreatment method with a short process that can handle low-quality oil slurry with high solids content, low aromatics, high sulfur, and high asphaltenes. In combined oil slurry pretreatment processes, solidification is generally the first step. However, due to the "coating" effect of polar substances in the oil slurry on the catalyst powder, deep solidification is difficult to achieve. When treating high-sulfur oil slurry, the general approach is to remove impurities by using the whole fraction of the oil slurry after solidification or by distillation to "cut off the head and tail," followed by hydrogenation of the middle fraction. When using whole fraction hydrogenation, the desulfurization rate is generally controlled at around 60% without losing aromatics, but the denitrification rate is relatively low. When using middle fraction hydrogenation, in addition to the overall low utilization rate of the oil slurry, the aromatics become lighter after hydrogenation, affecting the quality of subsequent carbonization products. Summary of the Invention

[0011] To address the aforementioned problems, the present invention aims to provide a method and system for selective deconsolidation and impurity removal pretreatment of oil slurries. This method can target and deeply deconsolidate and remove impurities from different types of oil slurries, obtaining high-quality aromatic-rich components with a relatively concentrated molecular weight distribution, which can be used as raw materials for the preparation of high-quality mesophase pitch and / or needle coke.

[0012] To achieve the above objectives, the present invention provides a method for selective deconsolidation and impurity removal pretreatment of oil slurry, the pretreatment method comprising:

[0013] Step 1: Separate the oil slurry into light and heavy components according to temperature;

[0014] Step 2: Selectively hydrogenate the light components according to their sulfur content;

[0015] Step 3: Mix the heavy components with an organic polar solvent to form a mixed heavy component, filter, and obtain the permeate side component and the concentrated side component;

[0016] Step 4: Filter and settle the mixed heavy components to obtain a permeate side component and a concentration side component. Mix the concentration side component with the heavy components and an organic polar solvent. Remove the solvent from the permeate side component to obtain the filtered slurry heavy components. Hydrogenate the filtered slurry heavy components to obtain hydrogenated slurry heavy components. Complete the selective deconsolidation and impurity removal pretreatment of the slurry.

[0017] In step 1 of the above method, the oil slurry used as raw material can be a catalytic oil slurry. Catalytic oil slurry has a complex composition; besides solid particles, if classified according to the four components of petroleum, its main components can be alkanes, aromatics, gums, and asphaltenes. Sulfides are distributed in alkanes, aromatics, gums, and asphaltenes, while nitrogen compounds are mainly distributed in gums and asphaltenes. If classified according to the type of elements in the compounds, they can be divided into hydrocarbons containing only carbon and hydrogen, and non-hydrocarbons containing sulfur, nitrogen, oxygen, and metal heteroatoms. Hydrocarbons, especially aromatics with a narrow ring number distribution range, are ideal components in oil slurry.

[0018] In step 1 of the above method, the process of separating the oil slurry into light and heavy components based on temperature is based on the distribution characteristics of various compounds and solids during the oil slurry distillation process. The light components have low sulfur and nitrogen content, low aromatic hydrocarbon density, and do not contain gum, asphaltenes, or solid particles. The heavy components have high aromatic hydrocarbon density and are enriched in sulfur, nitrogen, gum, asphaltenes, and solid particles. By separating the oil slurry into two components, the energy consumption and cost of subsequent processing can be effectively reduced, and processing efficiency can be improved.

[0019] In the above method, step 1, the separation can be achieved by distillation, and the separation is based on a temperature of 400-480℃. The specific temperature can be adjusted according to the initial boiling point of the oil slurry as long as the amount of light components and heavy components after separation is not significantly different.

[0020] In the above method, the light component obtained in step 1 generally does not contain solid particles.

[0021] In step 2 of the above method, by selectively hydrogenating the light components according to their sulfur content, the sulfur content can be further reduced, and the composition of aromatics can be avoided while denitrogenating, thereby improving the utilization value of the light components.

[0022] In the above method, step 2 typically involves hydrogenating light components with a sulfur content greater than 3000 ppm. In specific implementations, for light components with a sulfur content of 3000 ppm or less, hydrogenation may or may not be performed; generally, hydrogenation is avoided to prevent additional operating costs.

[0023] In the above method, in step 2, the temperature of the hydrogenation treatment can be 300-330℃, and the pressure of the hydrogenation treatment can be 2-4 MPa. In some specific embodiments, the hydrogenation treatment of the light component in step 2 can be a one-step hydrogenation treatment or a step-by-step hydrogenation treatment. When a step-by-step hydrogenation treatment is used, the conditions for each step of the hydrogenation treatment can be the same or different, as long as the treatment conditions of 300-330℃ and 2-4 MPa are met.

[0024] In the above method, in step 2, the active component of the catalyst used for the hydrogenation treatment can be selected from Group VIB and / or Group VIII. That is, the active component can include one or more of the following elements: chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). In some specific embodiments, the active component of the catalyst used in step 2 can include one or more of the following elements: Mo, Co, Ni, and W.

[0025] In the hydrogenation catalyst used in step 2 above, the active component accounts for more than or equal to 1.0% of the mass of the catalyst, for example, 4%-15%. The support in the hydrogenation catalyst may include alumina.

[0026] In step 3 of the above method, mixing the heavy components with an organic polar solvent allows for good dissolution and dispersion of polycyclic aromatic hydrocarbons and sulfur- and nitrogen-containing heteroatom compounds in the solvent, breaking down aggregates formed by hydrogen bonds and other forces in polar compounds to form individual molecules. Therefore, in a polar solvent environment, the catalyst powder encapsulated or adsorbed by polar molecules will be released due to dissolution and depolymerization. The process of mixing the heavy components with the organic polar solvent is a "physical depolymerization" process, which can release the solid particles "encapsulated" in the asphaltene. Subsequent filtration removes these solid particles, and the solvent removing the permeate side components yields the filtered heavy components of the slurry. This process can effectively remove solid particles from the slurry while improving the overall utilization rate of the slurry.

[0027] In the above method, in step 3, the molecule of the organic polar solvent may contain one or more combinations of sulfur atoms, nitrogen atoms, and oxygen atoms. In some specific embodiments, the number of sulfur atoms, nitrogen atoms, and oxygen atoms contained in the molecule of the organic polar solvent is independently 1-2.

[0028] In the above method, in step 3, the molecular weight of the organic polar solvent can be less than or equal to 100.

[0029] In the above method, in step 3, the organic polar solvent may include one or a combination of two or more of NMP (N-methyl-2-pyrrolidone), DMF (N,N-dimethylformamide), furfural, phenol, and DMSO (dimethyl sulfoxide).

[0030] In the above method, in step 3, the mass ratio of the organic polar solvent to the heavy component can be controlled to be 0.5-3:1.

[0031] In the above method, in step 3, the mixing temperature is 20-130℃, for example, it can be 50-130℃.

[0032] In the above method, in step 3, the mixing device can be a static device or a dynamic device, such as a static mixer, a mixing vessel, etc.

[0033] In the above method, step 4, the process of filtering and settling the mixed heavy components to obtain the permeate-side component and the concentrated-side component includes:

[0034] The mixed heavy components are filtered to obtain a permeation side component and a concentration side component. The concentration side component is subjected to sedimentation and desolidification to separate solid particles. The sedimentation and desolidification concentration side component is mixed with the heavy components and organic polar solvents described in step 3.

[0035] Alternatively, the mixed heavy components are subjected to sedimentation and desolidification to separate solid particles. The sedimented mixed heavy components are then filtered to obtain permeation-side and concentration-side components. The concentration-side components are then mixed with the heavy components and organic polar solvents described in step 3.

[0036] In the above method, in step 4, the settling time for sedimentation and deconsolidation is 10-60 minutes. The particle size of the solid particles removed during the sedimentation and deconsolidation process is generally above 20 μm.

[0037] In the above method, step 4, the filtration method may include dead-end filtration and / or cross-flow membrane filtration. In some specific embodiments, the membrane material of the cross-flow membrane filter may include one or more of alumina (such as inorganic ceramics), metal (the membrane material is sintered from metal particles), and silicon carbide.

[0038] In the above method, in step 4, the components with a particle size greater than or equal to the pore size of the material used for filtration are retained on the concentration side and form concentration side components; the components with a particle size smaller than the pore size of the material used for filtration can permeate through the membrane material and form permeation side components.

[0039] In the above method, step 4, the filtration can be performed using either single-stage or two-stage filtration. The single-stage filtration uses a material with a pore size ≤ 0.5 μm. The two-stage filtration includes a first-stage filtration and a second-stage filtration; the first-stage filtration uses a material with a pore size ≤ 0.5 μm, and the second-stage filtration uses a material with a pore size ≤ 0.1 μm.

[0040] In the above method, in step 4, the mass concentration of solids in the heavy components of the filtered oil slurry after primary filtration and solvent removal is ≤50ppm; the concentration of solids in the heavy components of the filtered oil slurry after two-stage filtration and solvent removal is ≤20ppm.

[0041] In step 4 of the above method, by mixing the concentrated side components after sedimentation and desolidification with heavy components and organic polar solvents, and then filtering them again to transfer them to the permeate side, solid particles can be transferred in an economical and energy-saving manner, thereby improving the utilization rate of the oil slurry.

[0042] In the above method, step 4, the solvent removal process on the permeate side, can be achieved through flash evaporation. After flash evaporation, the solvent and the filtered oil slurry heavy components are obtained separately. Flash evaporation relies on the boiling point difference between the heavy components and the solvent, releasing the material from a higher pressure to a lower pressure state, causing the lower-boiling-point substances to separate due to evaporation. The flash evaporation conditions depend on the boiling point of the solvent used. In some specific embodiments, the flash evaporation temperature can be 10°C lower than the solvent's boiling point, the pressure can be 10-50 kPa, and the flash evaporation environment is under negative pressure; for example, when the solvent is DMF, the flash evaporation temperature can be 130°C, and the pressure can be 10 kPa.

[0043] In the above method, step 4 may further include mixing the solvent removed from the permeation side with the heavy component and the organic polar solvent to form a mixed heavy component, thereby realizing the reuse of the solvent.

[0044] In step 4 of the above method, by performing deep hydrogenation treatment on the heavy components of the filtered oil slurry, sulfur and nitrogen can be removed and moderate aromatic saturation treatment can be achieved, thereby effectively reducing the sulfur and nitrogen content in the oil slurry. Furthermore, the heavy aromatics undergo moderate lightening, generating a structure that is conducive to the thermal polycondensation process and improving its value for further utilization.

[0045] In the above method, step 4, the hydrotreating of the heavy components of the filtered slurry, can be a one-step hydrotreating process or a step-by-step hydrotreating process, such as a two-step hydrotreating process. In a specific implementation, the choice between one-step or step-by-step hydrotreating can be made based on the asphaltene content and sulfur content. One-step hydrotreating has slightly lower efficiency but better economics; step-by-step hydrotreating has better efficiency but lower economics.

[0046] In some specific implementations, in step 4, the temperature of the one-step hydrogenation process can be controlled at 340-380°C, and the pressure can be controlled at 4-8 MPa.

[0047] In some specific implementations, step 4, the two-step hydrogenation process includes a first-step hydrogenation process and a second-step hydrogenation process. The temperature of the first-step hydrogenation process can be controlled at 300-330℃, and the pressure of the first-step hydrogenation process can be controlled at 2-4 MPa; the temperature of the second-step hydrogenation process can be controlled at 320-350℃, and the pressure of the second-step hydrogenation process can be controlled at 3-5 MPa.

[0048] In the above method, in step 4, the active component of the catalyst used in the hydrotreating of the heavy components of the filtered slurry can be selected from Group VIB and / or Group VIII; that is, the active component of the catalyst used in the first hydrotreating step and the second hydrotreating step is independently selected from Group VIB and / or Group VIII. Specifically, the active component of the catalyst used in the first hydrotreating step and / or the second hydrotreating step independently includes one or more of chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). In some specific embodiments, the active component of the catalyst used in the hydrotreating of the heavy components of the filtered slurry may include one or more of Mo, Co, Ni, and W.

[0049] In the above-mentioned hydrogenation catalyst, the active component accounts for more than or equal to 1.0% of the mass of the catalyst, for example, 4%-15%. The catalyst includes an active component and a support, and the support of the catalyst may include alumina.

[0050] The above method may further include step 5: mixing the light component (selectively hydrogenated) obtained in step 2 with the heavy component (hydrogenated in step 4) to obtain a refined oil slurry. This refined oil slurry can be used as a raw material for mesophase pitch or needle coke.

[0051] The pretreatment method provided by the present invention can improve the desolidification efficiency of oil slurry while reducing the desolidification depth, reducing energy consumption and cost, avoiding the generation of a large number of by-products, and improving the overall utilization rate of oil slurry; and while effectively reducing the sulfur and nitrogen content of heavy oil slurry with high sulfur and nitrogen content, it can increase the effective aromatic content and improve the utilization value of oil slurry.

[0052] According to a specific embodiment of the present invention, the above-mentioned selective deconsolidation and impurity removal pretreatment process for oil slurry specifically includes:

[0053] Step 1: Distill the oil slurry and separate the fraction into light and heavy components according to the fractionation temperature; the fractionation temperature is one of 400-480℃.

[0054] Step 2: Hydrogenate light components with a sulfur content greater than 3000 ppm. The hydrogenation conditions are: temperature 300-330℃, pressure 2-4 MPa. Hydrogenation is not required for light components with a sulfur content less than or equal to 3000 ppm.

[0055] Step 3: Mix the heavy component (enriched solid particles) obtained in Step 1 with an organic polar solvent at a mass ratio of 1:0.5-2 at 20-130℃ to obtain a mixed component; the above mixing process can promote the release of solid particles "encased" in the asphalt by the heavy component.

[0056] Step 4:

[0057] (1) Filter the mixed components to obtain a concentrated side component (enriched with solid particles) and a permeation side component (removed with solid particles); the concentrated side component is subjected to sedimentation and solidification and the solid particles are separated; the concentrated side component after sedimentation and solidification is reused in step 3 and mixed with heavy components and organic solvents to form a mixed heavy component; the concentrated side component after sedimentation and solidification enters the permeation side in part or all after being filtered again.

[0058] Alternatively, the mixed components can be sedimented and desolidified to separate solid particles. The sedimented and desolidified components can be filtered to obtain concentrated side components and permeation side components. The concentrated side components can be recycled to step 3 and mixed with heavy components and organic polar solvents to form mixed heavy components.

[0059] In the above process, filtration can be carried out using a single-stage filtration method or a two-stage filtration method;

[0060] (2) The permeate-side component is desolventized by flash evaporation. The desolventized solvent may be reused in step 3 and mixed with the heavy component and the organic polar solvent to form a mixed component. The mass concentration of solids in the permeate-side component (the heavy component of the filtered slurry) after primary filtration and solvent removal is ≤50ppm, and the mass concentration of solids in the permeate-side component after secondary filtration and solvent removal is ≤20ppm.

[0061] The permeate-side components after solvent removal are subjected to one-step or two-step hydrogenation treatment to obtain hydrogenated oil slurry heavy components;

[0062] The conditions for one-step hydrogenation are: temperature 340-380℃ and pressure 4-8MPa;

[0063] The two-step hydrogenation process includes a first-step hydrogenation process and a second-step hydrogenation process. The conditions for the first-step hydrogenation process are a temperature of 300-330℃ and a pressure of 2-4 MPa; the conditions for the second-step hydrogenation process are a temperature of 320-350℃ and a pressure of 3-5 MPa.

[0064] Step 5: Mix the light component obtained in Step 2 with the heavy component of the hydrogenated slurry obtained in Step 4 to form a refined slurry, thus completing the selective deconsolidation and impurity removal pretreatment of the slurry.

[0065] In the above steps, there is no special requirement for the order of steps 2 and 3. Step 2 can be performed first and then step 3, or step 3 can be performed first and then step 2, or steps 2 and 3 can be performed simultaneously.

[0066] The present invention also provides a selective desolidification and impurity removal pretreatment system for oil slurry, the system comprising:

[0067] The unit includes a segmentation unit, a mixing unit, a filtration unit, a sedimentation unit, a separation unit, a light component hydrogenation unit, and a heavy component hydrogenation unit.

[0068] The inlet of the segmentation unit receives slurry oil, the outlet of the heavy component of the segmentation unit is connected to the inlet of the mixing unit, and the outlet of the light component of the segmentation unit is connected to the inlet of the light component hydrogenation unit.

[0069] The outlet of the mixing unit is connected to the inlet of the filtration unit. The filtration unit has a concentration-side outlet and a permeation-side outlet. The concentration-side outlet of the filtration unit is connected to the inlet of the sedimentation unit, and the liquid phase outlet of the sedimentation unit is connected to the inlet of the mixing unit; or, the outlet of the mixing unit is connected to the inlet of the sedimentation unit, the liquid phase outlet of the sedimentation unit is connected to the inlet of the filtration unit, and the concentration-side outlet of the filtration unit is connected to the inlet of the mixing unit.

[0070] The solid phase outlet of the sedimentation unit is used to discharge solid particles, the permeate side outlet of the filtration unit is connected to the inlet of the separation unit, and the oil slurry outlet of the separation unit is connected to the inlet of the heavy component hydrogenation unit.

[0071] In the above system, the dividing unit can be a distillation unit.

[0072] In the above system, the separation unit is used to remove solvent from the permeate-side components. In some specific embodiments, the separation method may be flash evaporation, and correspondingly, the separation unit may be a flash evaporation unit.

[0073] In the above system, the solvent outlet of the separation unit can be connected to the inlet of the mixing unit.

[0074] The above-mentioned selective deconsolidation and impurity removal pretreatment system for oil slurry can realize the above-mentioned selective deconsolidation and impurity removal pretreatment method for oil slurry provided by the present invention.

[0075] The beneficial effects of this invention include:

[0076] 1. Highly Targeted and Energy-Saving: The pretreatment method provided by this invention separates the oil slurry into light and heavy components based on the distribution characteristics of various compounds and solids during oil slurry distillation, and then treats them separately, greatly improving the efficiency and effectiveness of solidification and impurity removal. The treatment method is simple and energy-efficient, and compared with existing technologies, it can significantly reduce processing costs and achieve energy conservation and emission reduction.

[0077] 2. High quality and high utilization rate of oil slurry: The pretreatment method provided by this invention introduces polar solvents for physical depolymerization and selective hydrogenation during the treatment process. Light components are selectively hydrogenated and desulfurized, heavy components are deeply hydrogenated and moderately saturated with aromatics. This effectively reduces the sulfur, nitrogen and aromatic content in the oil slurry. There are no other by-products except for solid particles. The oil slurry has high quality and high comprehensive utilization rate.

[0078] 3. Strong adaptability: The pretreatment method of the present invention is particularly suitable for treating heavy oil slurry with high sulfur and nitrogen content. It has strong adaptability and can meet the treatment needs of different types of oil slurry.

[0079] 4. The pretreatment method provided by the present invention can be used as a universal high-sulfur oil slurry pretreatment process. By combining decompression cutting, heavy component filtration and desolidation, and hydrogenation process unit technology, the above method can achieve "tailor-made" deep desolidation and deep impurity removal functions for oil slurries with different properties, compositions and sources, and obtain high-quality aromatic-rich components with relatively concentrated molecular weight distribution, which can be used as raw materials for the preparation of high-quality mesophase pitch and / or needle coke. Attached Figure Description

[0080] Figure 1 , Figure 2 This is a schematic diagram of the structure of the selective deconsolidation and impurity removal pretreatment system for oil slurry according to an embodiment of the present invention.

[0081] Symbol Explanation

[0082] Distillation unit 1, mixing unit 2, filtration unit 3, sedimentation unit 4, flash evaporation unit 5, light component hydrogenation unit 6, heavy component hydrogenation unit 7. Detailed Implementation

[0083] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0084] Embodiments of the present invention provide a selective deconsolidation and impurity removal pretreatment system for oil slurry, such as... Figure 1 , Figure 2 As shown, the system includes:

[0085] Distillation unit 1, mixing unit 2, filtration unit 3, sedimentation unit 4, flash evaporation unit 5, light component hydrogenation unit 6, and heavy component hydrogenation unit 7.

[0086] Distillation unit 1 serves as a fractionation unit, used to separate the oil slurry into light and heavy components based on the fractionation temperature. Distillation unit 1 is equipped with an inlet, a light component outlet, and a heavy component outlet.

[0087] Light component hydrogenation unit 6 is used to hydrogenate light components with high sulfur content (sulfur content greater than 3000 ppm), removing sulfur and nitrogen without affecting the aromatic composition, thus improving the utilization value of the light components. Light component hydrogenation unit 6 is equipped with an inlet and an outlet.

[0088] Mixing unit 2 is used to physically depolymerize heavy components with organic polar solvents, releasing solid particles encapsulated by asphaltene. Mixing unit 2 is equipped with an inlet and an outlet. Mixing unit 2 can be a static mixer, mixing vessel, etc.

[0089] Filter unit 3 is used to filter mixtures of heavy components and organic polar solvents. Filter unit 3 contains filter material with a permeation side and a concentration side on either side. Filter unit 3 can employ either single-stage or two-stage filtration. Single-stage filtration uses filter material with a pore size ≤0.5μm; two-stage filtration includes first-stage and second-stage filtration, where the filter material used in the first-stage filtration has a pore size ≤0.5μm, and the filter material used in the second-stage filtration has a pore size ≤0.1μm. Filter unit 3 has an inlet, a permeation-side outlet, and a concentration-side outlet.

[0090] Settling unit 4 is used for settling and solid-liquid separation. Specifically, settling unit 4 can be a settling tank. Settling unit 4 has an inlet, a liquid phase outlet, and a solid phase outlet. The solid phase outlet of settling unit 4 is used to discharge solid particles.

[0091] Flash evaporation unit 5 serves as a separation unit, used to remove solvent from the components discharged from the permeate side. Flash evaporation unit 5 is equipped with an inlet, an oil slurry outlet, and a solvent outlet.

[0092] The heavy component hydrogenation unit 7 is used for deep hydrogenation of the heavy components in the filtered slurry discharged from the flash evaporation unit 5, for the removal of sulfur and nitrogen and moderate aromatic saturation treatment. The heavy component hydrogenation unit 7 is equipped with an inlet and an outlet.

[0093] The connection relationships of the devices in the above system are as follows:

[0094] like Figure 1 and Figure 2 As shown, the inlet of distillation unit 1 receives oil slurry, the outlet of heavy components of distillation unit 1 is connected to the inlet of mixing unit 2, and the outlet of light components of distillation unit 1 is connected to the inlet of light component hydrogenation unit 6.

[0095] like Figure 1 As shown, the outlet of mixing unit 2 is connected to the inlet of filtration unit 3, the concentration-side outlet of filtration unit 3 is connected to the inlet of sedimentation unit 4, and the liquid phase outlet of sedimentation unit 4 is connected to the inlet of mixing unit 2; or, as shown... Figure 2 As shown, the outlet of mixing unit 2 is connected to the inlet of sedimentation unit 4, the liquid phase outlet of sedimentation unit 4 is connected to the inlet of filtration unit 3, and the concentration side outlet of filtration unit 3 is connected to the inlet of mixing unit 2.

[0096] like Figure 1 and Figure 2 As shown, the permeate outlet of the filtration unit 3 is connected to the inlet of the flash evaporation unit 5, the oil slurry outlet of the flash evaporation unit 5 is connected to the inlet of the heavy component hydrogenation unit 7, and the solvent outlet of the flash evaporation unit 5 is connected to the inlet of the mixing unit 2.

[0097] The light component hydrogenation unit 6 and the heavy component hydrogenation unit 7 may be filled with a hydrogenation catalyst, the composition of which is as follows: the active component element is selected from at least one of Group VIB and Group VIII; the mass percentage of the active component in the catalyst is more than 1.0% based on the element content.

[0098] The process of selective deconsolidation and impurity removal pretreatment of oil slurry in the above system is as follows:

[0099] Step 1: Distill the oil slurry in distillation unit 1, and separate the fraction into light and heavy components according to the fractionation temperature;

[0100] Step 2: Hydrogenate light components with a sulfur content greater than 3000 ppm in light component hydrogenation unit 6;

[0101] Step 3: In mixing unit 2, the heavy components obtained in step 1 are mixed with an organic polar solvent to obtain a mixed component;

[0102] Step 4:

[0103] (1) As Figure 1 As shown, the mixed components are filtered in the filtration unit 3 to obtain the concentrated side component and the permeation side component; the concentrated side component is settled and desolidified in the sedimentation unit 4 and the solid particles are separated; the concentrated side component after sedimentation and desolidification is reused in step 3 and mixed with the heavy components and organic solvent to form a mixed heavy components; the concentrated side component after sedimentation and desolidification enters the permeation side in part or all after being filtered again.

[0104] Or, such as Figure 2 As shown, the mixed components are settled and desolidified in the mixing unit 2 and solid particles are separated. The settled and desolidified components are filtered in the filtration unit 3 to obtain concentrated side components and permeation side components. The concentrated side components are recycled to step 3 and mixed with heavy components and organic polar solvents to form mixed heavy components.

[0105] (2) In the flash evaporation unit 5, the permeate side component is desolventized by flash evaporation. The desolventized solvent can be optionally reused in step 3 and mixed with the heavy component and organic polar solvent to form a mixed component. In the heavy component hydrogenation unit 7, the permeate side component (filtered oil slurry heavy component) after solvent removal is subjected to one-step hydrogenation treatment or two-step hydrogenation treatment to obtain hydrogenated oil slurry heavy component.

[0106] Step 5: Mix the light components obtained in Step 2 (light components with sulfur content less than or equal to 3000 ppm and light components with sulfur content greater than 3000 ppm after hydrogenation treatment) with the hydrogenated heavy components of the oil slurry obtained in Step 4 to form a refined oil slurry, thus completing the selective deconsolidation and impurity removal pretreatment of the oil slurry.

[0107] The pretreatment methods in the following embodiments can be performed in the above-mentioned selective deconsolidation and impurity removal pretreatment system for oil slurry.

[0108] Example 1

[0109] This embodiment provides a method for selective deconsolidation and impurity removal pretreatment of oil slurry, such as... Figure 1 As shown, the method includes:

[0110] (1) The oil slurry was distilled and cut at 440°C to obtain 60% light component and 40% heavy component by mass.

[0111] (2) The sulfur content in the light component is 8800 ppm. The light component is hydrogenated using a catalyst at 330°C and 2 MPa.

[0112] (3) DMF polar solvent is used as physical depolymerization solvent for heavy components. The mass ratio of physical depolymerization solvent to heavy components is 1.5:1. After the oil slurry and DMF are heated to 90°C, they are mixed in a static mixer to obtain a mixture.

[0113] The mixture exiting the static mixer enters a cross-flow membrane filtration unit, which uses a metal membrane tube with a filtration precision (i.e., material pore size) of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component undergoes sedimentation and desolidification before returning to the static mixer to mix with the heavy components and DMF, and then undergoes a second filtration.

[0114] (4) The permeate slurry is preheated to 130°C and enters the flash evaporation unit. Flash evaporation is carried out at a pressure of 10 kPa. After the solvent is recovered, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to one-step hydrogenation treatment at a temperature of 380°C and a pressure of 4 MPa. The recovered solvent is returned to the static mixer to mix with the heavy components and DMF.

[0115] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as raw material for needle coke.

[0116] The active component of the hydrogenation catalyst used in step (2) contains Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 12% of the mass of the catalyst, and the remainder is an alumina support.

[0117] The active component of the hydrogenation catalyst used in step (4) contains Mo and Ni elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 10% of the mass of the catalyst, and the remainder is an alumina support.

[0118] The slurry used in this embodiment is a high-sulfur heavy slurry 1. The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. Specifically, when the slurry used in this embodiment is cut at an AET temperature (equivalent to atmospheric pressure) of 440°C, the cumulative yield of the light fraction is 60%, and the cumulative yield of the heavy fraction is 40%. A solvent with a mass of 1.5 times the heavy fraction is used in the physical depolymerization and filtration stages. The permeate recovery rate is 95%, with a solid particulate content of 30 ppm and a solidification rate of 98%. The refined slurry contains 5.5% more tri- and tetra-cyclic aromatic hydrocarbons (substances with three or four parallel aromatic rings, such as phenanthrene and pyrene compounds), achieving an overall desulfurization rate of 72% and a denitrification rate of 22%. The treatment process produces no byproducts other than solid particles, and the slurry utilization rate is 100%.

[0119] Example 2

[0120] This embodiment provides a selective deconsolidation and impurity removal pretreatment method for oil slurry. The oil slurry treated in this embodiment is the same as that in Embodiment 1. Steps (1), (2), and (5) of the method provided in this embodiment are the same as steps (1), (2), and (5) of Embodiment 1. Steps (3) and (4) of this embodiment are as follows:

[0121] Step (3): DMF, a polar solvent, is used as the physical depolymerization solvent for the heavy components. The mass ratio of the physical depolymerization solvent to the heavy components is 1.5:1. After the oil slurry and DMF are heated to 90°C, they are mixed in a static mixer to obtain a mixture.

[0122] The mixture exiting the static mixer enters the filtration unit, which employs a two-stage cross-flow membrane filtration system. The first stage uses a metal-ceramic membrane with a filtration precision of 0.5 μm, while the second stage uses an inorganic ceramic membrane with a filtration precision of 0.1 μm. The permeate side of the first stage undergoes secondary filtration, yielding permeate-side components from the second stage and concentrated-side components from both stages. The concentrated-side components undergo sedimentation and deconsolidation before returning to the mixing unit for further filtration.

[0123] Step (4): The permeate slurry is preheated to 130°C and enters the flash evaporation unit. Flash evaporation is carried out at a pressure of 10 kPa. After solvent recovery, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to two-step hydrogenation treatment. The temperature of the first step hydrogenation treatment is 320°C and the pressure is 3 MPa. The temperature of the second step hydrogenation treatment is 360°C and the pressure is 6 MPa. The recovered solvent is returned to the static mixer to mix with the heavy components and DMF.

[0124] The active components of the first-step hydrogenation catalyst used in step (4) contain Mo and W elements. Based on the total mass of the catalyst, the active components (based on element content) account for 6% of the mass of the catalyst, and the remainder is alumina support. Based on the total mass of the catalyst, the active components of the second-step hydrogenation catalyst are Ni and Mo. The active components (based on element content) account for 12% of the mass of the catalyst, and the remainder is alumina support.

[0125] The physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. Due to the two-stage filtration, the second-stage filtration membrane has high separation accuracy, with a permeate recovery rate of 80%, a solid particulate content of 10 ppm, and a solidification rate of 99%. A two-step hydrogenation process increases the tri- and tetra-cyclic aromatic hydrocarbon content in the refined slurry by 9.2%, achieving an overall desulfurization rate of 80% and a denitrification rate of 30%. The treatment process produces no byproducts other than solid particles, and the slurry utilization rate is 100%.

[0126] Example 3

[0127] This embodiment provides a selective deconsolidation and impurity removal pretreatment method for oil slurry, using high-sulfur heavy oil slurry 2, such as... Figure 1 As shown, the method includes the following steps:

[0128] (1) The oil slurry was distilled and cut at 420°C to obtain 30% light components and 70% heavy components.

[0129] (2) The sulfur content in the light component is 9500 ppm. The light component is hydrogenated using a catalyst at 300℃ and 4MPa.

[0130] (3) The heavy components are treated with furfural polar solvent as physical depolymerization solvent. The mass ratio of depolymerization solvent to heavy components is 1.0:1. After the oil slurry and furfural are heated to 100°C, they are mixed in a static mixer to obtain a mixture.

[0131] The mixture exiting the static mixer enters a cross-flow membrane filtration unit, which uses an inorganic ceramic membrane tube with a filtration precision of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-diameter solids and a concentrated-side component enriched with large-diameter solids are obtained. The concentrated-side component undergoes sedimentation and desolvation before being returned to the static mixer to mix with the heavy components and furfural, and then undergoes a second filtration.

[0132] (4) The permeate slurry enters the flash evaporation unit for flash evaporation. The flash evaporation temperature is 10°C lower than the solvent boiling point, and the pressure is 10-50 kPa. The flash evaporation unit is under negative pressure. After recovering the solvent, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to step-by-step hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 2 MPa. The second hydrogenation treatment temperature is 340°C and the pressure is 8 MPa. The recovered solvent is returned to the static mixer to mix with the heavy components and furfural.

[0133] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as raw material for needle coke.

[0134] The active component of the hydrogenation catalyst used in step (2) contains Co, Mo and W elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 8% of the mass of the catalyst, and the remainder is an alumina support.

[0135] The active component of the hydrogenation catalyst used in step (4) contains Ni, Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 14% of the mass of the catalyst, and the remainder is an alumina support.

[0136] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, when the slurry is cut at an AET temperature of 420°C, the cumulative yield of the light fraction is 30%, and the cumulative yield of the heavy fraction is 70%. A solvent with a mass equal to 1.0 times the mass of the heavy fraction is used in the physical depolymerization and filtration stages. The permeate recovery rate is 85%, with a solid particulate content of 50 ppm and a solidification rate of 95%. The refined slurry shows a 10.0% increase in tri- and tetra-cyclic aromatic hydrocarbons, an overall desulfurization rate of 80%, and a denitrification rate of 40%. The process produces no byproducts other than solid particles, and the slurry utilization rate is 100%.

[0137] Example 4

[0138] This embodiment provides a selective desolidification and impurity removal pretreatment method for oil slurry, using low-sulfur light oil slurry, such as... Figure 1 As shown, the method includes the following steps:

[0139] (1) The oil slurry was distilled and cut at 400°C to obtain 60% light components and 40% heavy components.

[0140] (2) The sulfur content in the light component is 1500 ppm or less than 3000 ppm, so no hydrogenation is required;

[0141] (3) The heavy components are treated with furfural polar solvent as physical depolymerization solvent. The mass ratio of depolymerization solvent to heavy components is 0.5:1. After the oil slurry and furfural are heated to 50°C, they are mixed in a static mixer to obtain a mixture.

[0142] The mixture exiting the static mixer enters a cross-flow membrane filtration unit, which uses an inorganic ceramic membrane tube with a filtration precision of 0.1 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component undergoes sedimentation and desolidification before being returned to the static mixer to be mixed with the heavy components and DMF, and then filtered again.

[0143] (4) The permeate slurry enters the flash evaporation unit for flash evaporation. The flash evaporation temperature is 10°C lower than the solvent boiling point, and the pressure is 10-50 kPa. The flash evaporation unit is under negative pressure. After the solvent is recovered, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to one-step hydrogenation treatment. The hydrogenation treatment temperature is 340°C and the pressure is 4 MPa.

[0144] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as mesophase asphalt raw material.

[0145] The active component of the hydrogenation catalyst used in step (2) contains Mo and W elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 4% of the mass of the catalyst, and the remainder is an alumina support.

[0146] The active component of the hydrogenation catalyst used in step (4) contains Ni and Mo elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 8% of the mass of the catalyst, and the remainder is an alumina support.

[0147] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry, when cut at an AET temperature of 400°C, achieved a light fraction cumulative yield of 60% and a heavy fraction cumulative yield of 40%. The solvent used in the physical depolymerization and filtration stages was 0.5 times the mass of the heavy fraction. The permeate recovery rate was 90%, with a solid particulate content of 10 ppm and a solidification rate of 99%. The refined slurry showed a 2% increase in tri- and tetra-cyclic aromatic hydrocarbons, an overall desulfurization rate of 65%, and a denitrification rate of 10%. The process produced no byproducts other than solid particles, and the slurry utilization rate was 100%.

[0148] Example 5

[0149] This embodiment provides a method for selective deconsolidation and impurity removal pretreatment of oil slurry. The type of oil slurry treated in this embodiment is the same as that treated in Example 4. Figure 2As shown, steps (1), (2), (4), and (5) of the preprocessing method in this embodiment are basically the same as steps (1), (2), (4), and (5) in embodiment 4. Step (3) of this embodiment is as follows:

[0150] Step (3): The heavy component is treated with NMP as a polar solvent for physical depolymerization, with a mass ratio of depolymerization solvent to heavy component of 2:1. After the oil slurry and NMP are heated to 50°C, they are stirred mechanically in a mixing vessel for 30 minutes. Then, they are transferred to a sedimentation unit for sedimentation and desolidification. The supernatant obtained from sedimentation and desolidification is transferred to a cross-flow membrane filtration unit using an inorganic ceramic membrane tube with a filtration accuracy of 0.1 μm. After filtration, permeate-side components and concentrate-side components are obtained. The concentrate-side components are returned to the mixing vessel to be mixed with the heavy component and NMP and then filtered again.

[0151] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry, when cut at an AET temperature of 400℃, achieved a light fraction cumulative yield of 60% and a heavy fraction cumulative yield of 40%. The solvent used in the physical depolymerization and filtration stages was twice the mass of the heavy fraction. The permeate recovery rate was 95%, with a solid particulate content of 10 ppm and a solidification rate exceeding 98%. The refined slurry showed a 2% increase in tri- and tetra-cyclic aromatic hydrocarbons, an overall desulfurization rate of 65%, and a denitrification rate of 6%. The process produced no byproducts other than solid particles, and the slurry utilization rate was 100%.

[0152] Example 6

[0153] This embodiment provides a selective desolidification and impurity removal pretreatment method for oil slurry, using high-sulfur heavy oil slurry 3, such as... Figure 1 As shown, the preprocessing method includes the following steps:

[0154] (1) The oil slurry was distilled and cut at 480°C to obtain 80% light components and 20% heavy components.

[0155] (2) The sulfur content in the light component is 10200 ppm. A two-step hydrogenation treatment is carried out using a light component hydrogenation catalyst. The first step hydrogenation treatment temperature is 300℃ and 4MPa, and the second step hydrogenation treatment temperature is 350℃ and 3MPa.

[0156] (3) DMF polar solvent was used as the physical depolymerization solvent for the heavy components. The mass ratio of the depolymerization solvent to the heavy components was 2.0:1. After the oil slurry and DMF were heated to 120°C, they were stirred mechanically in the mixing vessel for 30 minutes to obtain the mixture.

[0157] The mixture enters a cross-flow membrane filtration unit, using an inorganic ceramic membrane tube with a filtration precision of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component undergoes sedimentation and desolvation before being returned to the mixing vessel to be mixed with the heavy components and DMF for further filtration.

[0158] (4) The permeate slurry enters the flash evaporation unit for flash evaporation. The flash evaporation temperature is 10°C lower than the solvent boiling point, and the pressure is 10-50 kPa. The flash evaporation unit is under negative pressure. After the solvent is recovered, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to step-by-step hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 4 MPa. The second hydrogenation treatment temperature is 350°C and the pressure is 5 MPa.

[0159] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as raw material for needle coke.

[0160] The active component of the hydrogenation catalyst used in step (2) contains Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 9% of the mass of the catalyst, and the remainder is an alumina support.

[0161] The active component of the hydrogenation catalyst used in step (4) contains Ni, Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 15% of the mass of the catalyst, and the remainder is an alumina support.

[0162] The specific physical properties of the slurry oil and refined slurry oil in this embodiment are shown in Table 1. In this embodiment, when the slurry oil was cut at an AET temperature of 480℃, the cumulative yield of the light fraction was 80%, and the cumulative yield of the heavy fraction was 20%. A solvent with a mass equal to 2.0 times the mass of the heavy fraction was used in the physical depolymerization and filtration stages. The permeate recovery rate was 90%, with a solid particulate content of 50 ppm, achieving a solidification rate of 95%. The overall desulfurization rate of the slurry oil reached 85%, and the denitrification rate reached 35%. Due to the increased hydrogenation depth, the content of tri- and tetra-cyclic aromatic hydrocarbons in the refined slurry oil did not increase. The processing yielded no other byproducts besides solid particles, and the slurry oil utilization rate was 100%.

[0163] Comparative Example 1

[0164] This comparative example provides a selective desolidification and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 3. The difference between the oil slurry pretreatment method provided in this comparative example and the method in Example 3 is that the oil slurry is not cut, and the entire fraction is filtered and hydrogenated.

[0165] Step (1): The oil slurry was not cut;

[0166] Step (2): The whole fraction is treated with DMF as a polar solvent for physical depolymerization, with a depolymerization solvent to oil slurry mass ratio of 0.5:1. The whole fraction and DMF are mixed in a static mixer, and the mixture enters a cross-flow membrane filtration unit using an inorganic ceramic membrane tube with a filtration accuracy of 0.5 μm. After filtration, a permeate-side component and a concentrate-side component are obtained. The concentrate-side component is settled and desolidified, then returned to the static mixer to be mixed with the whole fraction and DMF for further filtration.

[0167] Step (3): After the solvent is recovered by the flash evaporation unit, the complete component of the slurry is obtained (flash evaporation conditions are the same as in Example 3). The complete component of the slurry is subjected to stepwise hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 2MPa; the second hydrogenation treatment temperature is 340°C and the pressure is 8MPa. The catalyst used for hydrogenation treatment is the same as in Example 3. The recovered solvent is returned to the static mixer and mixed with the whole fraction and DMF.

[0168] The entire composition of the hydrotreated slurry is used as the refined slurry.

[0169] The physical properties of the slurry oil and refined slurry oil used in this comparative example are shown in Table 1. The slurry oil used in this comparative example was not cut; the entire fraction underwent physical depolymerization and filtration. Due to the consistent membrane filtration precision, the solidification rate was comparable, reaching 95%. However, the solvent consumption was high, and the filtration process and permeate flash evaporation solvent recovery process involved large volumes and high energy consumption. The entire fraction underwent hydrogenation, with a high degree of hydrogenation, resulting in a 5.3% loss of tri- and tetra-cyclic aromatic hydrocarbons in the refined slurry oil. The treatment process produced no byproducts other than solid particles, and the slurry oil utilization rate was 100%.

[0170] Comparative Example 2

[0171] This comparative example provides a selective desolidification and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 3. The difference between the pretreatment method provided in this comparative example and the method in Example 3 lies in the order of cutting and filtering. The specific process is as follows:

[0172] Step (1): The oil slurry was not cut, and no polar solvent was used for physical depolymerization. The entire oil slurry was directly introduced into a cross-flow membrane filtration unit for desolidification. An inorganic ceramic membrane tube was used, with a filtration accuracy of 0.5 μm. After filtration, a permeate side component and a concentrate side component were obtained. In the concentrate side component, the solid particles and the asphaltene in the oil slurry were in a "coupling" state and could not be settled and desolidified.

[0173] Step (2): After the solvent is recovered in the flash evaporation unit, the total components of the slurry are obtained (flash evaporation conditions are the same as in Example 3). The slurry is then cut at AET 420°C to obtain 30% light components and 70% heavy components. The light and heavy components are then hydrogenated separately under the same conditions as in Example 3. The hydrogenated light and heavy components are then mixed to obtain the refined slurry.

[0174] The specific physical properties of the oil slurry and refined oil slurry in this comparative example are shown in Table 1. The oil slurry used in this comparative example was not cut and was not physically depolymerized using polar solvents. After solvent recovery on the permeation side, 85% of the oil slurry was obtained, and 15% of the concentrated side component was generated, which could not be further desolidified and utilized, resulting in an oil slurry utilization rate of only 85%.

[0175] Comparative Example 3

[0176] This comparative example provides a selective desolidification and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 3. The difference between the pretreatment method provided in this comparative example and Example 3 is that no cutting was performed before or after filtration, and no solvent was added during the filtration process. The specific process is as follows:

[0177] Step (1): The oil slurry was not cut, and no polar solvent was used for physical depolymerization. The entire oil slurry was directly introduced into a cross-flow membrane filtration unit for desolidification. An inorganic ceramic membrane tube was used, with a filtration accuracy of 0.5 μm. After filtration, a permeate side component and a concentrate side component were obtained. In the concentrate side component, the solid particles and the asphaltene in the oil slurry were in a "coupling" state and could not be settled and desolidified.

[0178] Step (2): After the solvent is recovered by the flash evaporation unit, the slurry on the permeate side is obtained as the complete slurry component (flash evaporation conditions are the same as in Example 3). The component is not cut. The complete component is subjected to step-by-step hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 2MPa; the second hydrogenation treatment temperature is 340°C and the pressure is 8MPa. The catalyst used for hydrogenation treatment is the same as in Example 3. The slurry after hydrogenation treatment is used as refined slurry.

[0179] The physical properties of the slurry oil and refined slurry oil used in this comparative example are shown in Table 1. The slurry oil used in this comparative example was not cut, and no polar solvent was used for physical depolymerization. After solvent recovery from the permeate side, the slurry oil contained 85% of the components, while the concentrated side contained 15%, which could not be further desoldered or utilized, resulting in a slurry oil utilization rate of only 85%. Due to the hydrogenation of the entire fraction and the high degree of hydrogenation, the refined slurry oil contained a 5.3% loss of tri- and tetra-cyclic aromatic hydrocarbons.

[0180] Comparative Example 4

[0181] This comparative example provides a selective deconsolidation and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 3. The difference between the oil slurry pretreatment method provided in this comparative example and Example 3 is that no further deconsolidation is performed on the concentrated side components after filtration. The specific process is as follows:

[0182] Steps (1) and (2) are the same as steps (1) and (2) in Example 3;

[0183] Step (3): Furfural polar solvent is used as the physical depolymerization solvent for the heavy components. The mass ratio of the depolymerization solvent to the heavy components is 1.0:1. After the oil slurry and furfural are heated to 100°C, they are mixed in a static mixer to obtain a mixture.

[0184] The mixture exiting the static mixer enters the cross-flow membrane filtration unit, which uses an inorganic ceramic membrane tube with a filtration accuracy of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component is not subjected to sedimentation and desolvation but is directly returned to the static mixer to be mixed with the heavy components and furfural for further filtration.

[0185] Steps (4) and (5) are the same as steps (4) and (5) in Example 3.

[0186] The physical properties of the oil slurry and refined oil slurry in this comparative example are shown in Table 1. Since the components on the concentrated side were not subjected to sedimentation and desolidification, the content of solid particles in the material processed by the filtration unit became higher and higher, and the permeation yield became lower and lower, resulting in the inability to continuously filter the oil slurry and low utilization of the oil slurry.

[0187] Table 1

[0188]

[0189]

[0190] In Table 1, the yields of light and heavy components represent the light and heavy weights of the feedstock slurry, and the sulfur content indicates whether the feedstock slurry is high in sulfur. In slurry utilization, the focus is mainly on the ideal components containing 3-4 ring aromatics, and the non-ideal components, primarily solid particles, sulfur, and nitrogen. This invention primarily focuses on the increase or decrease of ideal components during the removal of non-ideal components.

[0191] The above results demonstrate that the pretreatment method provided by this invention selectively and deeply desolidifies and removes impurities based on the composition characteristics of the oil slurry. This method can minimize the processing volume of the desolidification and impurity removal units, generate no byproducts other than solid particles, achieve high oil slurry utilization, and is economical and environmentally friendly. It is especially suitable for treating heavy oil slurries with high sulfur and nitrogen content.

Claims

1. A method for selective deconsolidation and impurity removal pretreatment of oil slurry, the pretreatment method comprising: Step 1: Separate the oil slurry into light and heavy components according to temperature; Step 2: Selectively hydrogenate the light components according to their sulfur content; Step 3: Mix the heavy components with an organic polar solvent to form a mixed heavy component; Step 4: Filter and settle the mixed heavy components to obtain a permeate side component and a concentrated side component. Mix the concentrated side component with the heavy components and an organic polar solvent. Remove the solvent from the permeate side component to obtain the filtered oil slurry heavy components. Hydrogenation treatment was performed on the heavy components of the filtered oil slurry to obtain hydrogenated heavy components of the oil slurry; this completed the selective desolidification and impurity removal pretreatment of the oil slurry.

2. The preprocessing method according to claim 1, wherein, In step 1, the separation is achieved by distillation, and the separation is based on a temperature of 400-480℃.

3. The preprocessing method according to claim 1, wherein, In step 2, light components with a sulfur content greater than 3000 pppm are subjected to hydrogenation treatment.

4. The pretreatment method according to claim 1 or 3, wherein, In step 2, the temperature of the hydrogenation treatment is 300-330℃, and the pressure of the hydrogenation treatment is 2-4MPa.

5. The preprocessing method according to claim 1, wherein, The active components of the catalysts used in the hydrogenation treatment in step 2 and / or step 3 are each selected from Group VIB and / or Group VIII. Based on elemental content, the active component accounts for more than or equal to 1.0% of the mass of the catalyst.

6. The preprocessing method according to claim 1, wherein, In step 3, the molecule of the organic polar solvent contains one or more combinations of sulfur atoms, nitrogen atoms, and oxygen atoms. The organic polar solvent contains 1-2 sulfur atoms, nitrogen atoms, and oxygen atoms in its molecules. The molecular weight of the organic polar solvent is less than or equal to 100.

7. The pretreatment method according to claim 1 or 6, wherein, The organic polar solvent includes one or more of NMP, DMF, furfural, phenol, and DMSO.

8. The preprocessing method according to claim 1, wherein, In step 3, the mass ratio of the organic polar solvent to the heavy component is 0.5-3:

1.

9. The preprocessing method according to claim 1, wherein, In step 3, the mixing temperature is 20-130℃.

10. The preprocessing method according to claim 1, wherein, Step 4, the process of filtering and settling the mixed heavy components to obtain the permeate-side component and the concentrated-side component includes: The mixed heavy components are filtered to obtain a permeable side component and a concentrated side component. The concentrated side component is subjected to sedimentation and desolidification to separate solid particles. The concentrated side component after sedimentation and desolidification is mixed with the heavy components and an organic polar solvent. Alternatively, the mixed heavy components are subjected to sedimentation and desolidification to separate solid particles. The sedimented mixed heavy components are then filtered to obtain permeate-side and concentration-side components. The concentration-side components are then mixed with the heavy components and an organic polar solvent.

11. The preprocessing method according to claim 1, wherein, In step 4, the settling time for the settling and deconsolidation process is 10 min to 60 min.

12. The preprocessing method according to claim 1, wherein, In step 4, the filtration method includes dead-end filtration and / or cross-flow membrane filtration; The membrane material of the cross-flow membrane filtration includes one or more of alumina, metal, and silicon carbide.

13. The preprocessing method according to claim 1, wherein, In step 4, the filtration is performed using either primary or secondary filtration. The material used in the primary filtration has a pore size ≤ 0.5 μm; The secondary filtration includes a first-stage filtration and a second-stage filtration. The material used in the first-stage filtration has a pore size ≤ 0.5 μm, and the material used in the second-stage filtration has a pore size ≤ 0.1 μm.

14. The preprocessing method according to claim 11, wherein, In step 4, the solids concentration in the heavy components of the filtered oil slurry after primary filtration and solvent removal is ≤50ppm; the solids concentration in the heavy components of the filtered oil slurry after secondary filtration and solvent removal is ≤20ppm.

15. The preprocessing method according to claim 1, wherein, In step 4, the hydrogenation process can be a one-step hydrogenation process or a two-step hydrogenation process; The temperature of the one-step hydrogenation process is 340-380℃, and the pressure is 4-8MPa. The two-step hydrogenation process includes a first-step hydrogenation process and a second-step hydrogenation process; the temperature of the first-step hydrogenation process is 300-330℃, and the pressure of the first-step hydrogenation process is 2-4MPa; the temperature of the second-step hydrogenation process is 320-350℃, and the pressure of the second-step hydrogenation process is 3-5MPa.

16. The preprocessing method according to claim 1, wherein, Step 4 also includes mixing the solvent removed from the permeation side with the heavy component and the organic polar solvent to form a mixed heavy component.

17. The preprocessing method according to claim 1, wherein, The method further includes: step 5, mixing the light component obtained in step 2 and the hydrogenated oil slurry heavy component obtained in step 4 to form a refined oil slurry.

18. A selective deconsolidation and impurity removal pretreatment system for oil slurry, the system comprising: The unit includes a segmentation unit, a mixing unit, a filtration unit, a sedimentation unit, a separation unit, a light component hydrogenation unit, and a heavy component hydrogenation unit. The heavy component outlet of the segmentation unit is connected to the inlet of the mixing unit, and the light component outlet of the segmentation unit is connected to the inlet of the light component hydrogenation unit. The outlet of the mixing unit is connected to the inlet of the filtration unit, the concentration-side outlet of the filtration unit is connected to the inlet of the sedimentation unit, and the liquid phase outlet of the sedimentation unit is connected to the inlet of the mixing unit; or, the outlet of the mixing unit is connected to the inlet of the sedimentation unit, the liquid phase outlet of the sedimentation unit is connected to the inlet of the filtration unit, and the concentration-side outlet of the filtration unit is connected to the inlet of the mixing unit. The solid phase outlet of the sedimentation unit is used to discharge solid particles, the permeate side outlet of the filtration unit is connected to the inlet of the separation unit, and the oil slurry outlet of the separation unit is connected to the inlet of the heavy component hydrogenation unit.

19. The system according to claim 18, wherein, The solvent outlet of the separation unit is connected to the inlet of the mixing unit.

20. The system according to claim 18, wherein, The selective deconsolidation and impurity removal pretreatment system for oil slurry can realize the selective deconsolidation and impurity removal pretreatment method for oil slurry as described in any one of claims 1-17.

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